Who owns MDXH (MDXH)
Which tracked institutional funds hold MDXH, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MDXH company fundamentals →
Ownership as of the 2026-Q1 13F filings. 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
The tracked-fund tape on MDXH is one-sided between 2025-Q4 and 2026-Q1: 2 added or opened and 13 trimmed or exited — on balance reducing.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
MDXH’s largest tracked holder by dollar value, Bleichroeder LP, sizes it at 2.9% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 2.9pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MDXH divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2025-Q4 and 2026-Q1, across 50 tracked filers holding MDXH, 21 increased or opened the position and 32 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in MDXH between the 2025-Q4 and 2026-Q1 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
Full exits 1
- FreeGulliver LLC$1M
Largest adds
- Mink Brook Asset Management LLC$2M
- MILLENNIUM MANAGEMENT LLC$836K
Largest trims
- Bleichroeder LP$9M
- AWM Investment Company, Inc.$7M
- MVM Partners, LLC$6M
- Samjo Management, LLC$2M
- PERKINS CAPITAL MANAGEMENT INC$2M
- KENNEDY CAPITAL MANAGEMENT LLC$939K
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| Bleichroeder LP | 7,378,333 | $17M | 28.1% | 2026-Q1 |
| AWM Investment Company, Inc. | 5,221,282 | $12M | 19.9% | 2026-Q1 |
| MVM Partners, LLC | 4,700,457 | $11M | 17.8% | 2026-Q1 |
| PERKINS CAPITAL MANAGEMENT INC added | 1,476,441 | $3M | 5.6% | 2026-Q1 |
| Samjo Management, LLC added | 1,449,450 | $3M | 5.5% | 2026-Q1 |
| Mink Brook Asset Management LLC added | 1,203,454 | $3M | 4.6% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 544,728 | $1M | 2.1% | 2026-Q1 |
| NORTHERN TRUST CORP trimmed | 494,523 | $1M | 1.9% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC added | 304,700 | $701K | 1.2% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 267,692 | $616K | 1.0% | 2026-Q1 |
| Panoramic Capital, LLC | 238,668 | $549K | 0.9% | 2026-Q1 |
| KENNEDY CAPITAL MANAGEMENT LLC trimmed | 205,438 | $473K | 0.8% | 2026-Q1 |
| LANDSCAPE CAPITAL MANAGEMENT, L.L.C. new | 163,655 | $376K | 0.6% | 2026-Q1 |
| Shay Capital LLC trimmed | 150,000 | $345K | 0.6% | 2026-Q1 |
| BlackRock, Inc. added | 104,321 | $240K | 0.4% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 98,619 | $227K | 0.4% | 2026-Q1 |
| 683 Capital Management, LLC trimmed | 97,000 | $223K | 0.4% | 2026-Q1 |
| Russell Investments Group, Ltd. trimmed | 68,871 | $158K | 0.3% | 2026-Q1 |
| Hudson Bay Capital Management LP added | 62,497 | $144K | 0.2% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 59,634 | $137K | 0.2% | 2026-Q1 |
| MARSHALL WACE, LLP trimmed | 50,166 | $115K | 0.2% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 43,492 | $100K | 0.2% | 2026-Q1 |
| XTX Topco Ltd trimmed | 37,715 | $87K | 0.1% | 2026-Q1 |
| AlphaCentric Advisors LLC trimmed | 32,951 | $76K | 0.1% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC | 29,185 | $67K | 0.1% | 2026-Q1 |
| Catalyst Funds Management Pty Ltd new | 28,046 | $65K | 0.1% | 2026-Q1 |
| FIRST MANHATTAN CO. LLC. | 27,000 | $62K | 0.1% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP trimmed | 21,184 | $49K | 0.1% | 2026-Q1 |
| Point72 Asset Management, L.P. trimmed | 20,767 | $48K | 0.1% | 2026-Q1 |
| CITIGROUP INC trimmed | 18,945 | $44K | 0.1% | 2026-Q1 |
| MORGAN STANLEY trimmed | 16,384 | $38K | 0.1% | 2026-Q1 |
| AXQ CAPITAL, LP new | 15,954 | $37K | 0.1% | 2026-Q1 |
| Diametric Capital, LP new | 13,203 | $30K | 0.1% | 2026-Q1 |
| OMERS ADMINISTRATION Corp trimmed | 11,800 | $27K | 0.0% | 2026-Q1 |
| HRT FINANCIAL LP new | 11,323 | $26K | 0.0% | 2026-Q1 |
| GSA CAPITAL PARTNERS LLP trimmed | 11,092 | $26K | 0.0% | 2026-Q1 |
| PEAPACK GLADSTONE FINANCIAL CORP new | 11,011 | $25K | 0.0% | 2026-Q1 |
| Lido Advisors, LLC added | 10,497 | $24K | 0.0% | 2026-Q1 |
| Cambridge Investment Research Advisors, Inc. | 10,000 | $23K | 0.0% | 2026-Q1 |
| Intesa Sanpaolo Wealth Management | 10,000 | $23K | 0.0% | 2026-Q1 |
| FEDERATED HERMES, INC. trimmed | 702 | $2K | 0.0% | 2026-Q1 |
| BARCLAYS PLC added | 694 | $2K | 0.0% | 2026-Q1 |
| WELLS FARGO & COMPANY/MN | 200 | $460 | 0.0% | 2026-Q1 |
| UBS Group AG trimmed | 176 | $405 | 0.0% | 2026-Q1 |
| Monetary Solutions, Ltd | 85 | $196 | 0.0% | 2026-Q1 |
| DEUTSCHE BANK AG\ new | 50 | $115 | 0.0% | 2026-Q1 |
| SBI Securities Co., Ltd. | 29 | $67 | 0.0% | 2026-Q1 |
| Farther Finance Advisors, LLC | 10 | $22 | 0.0% | 2026-Q1 |
| Caitong International Asset Management Co., Ltd new | 7 | $16 | 0.0% | 2026-Q1 |
| ROYAL BANK OF CANADA new | 60 | — | 0.0% | 2026-Q1 |
| FreeGulliver LLC added | 317,894 | $1M | 1.9% | 2025-Q4 stale |
| Informed Momentum Co LLC new | 127,780 | $594K | 1.0% | 2025-Q3 stale |
| JANE STREET GROUP, LLC added | 92,078 | $329K | 0.5% | 2025-Q4 stale |
| Calamos Advisors LLC added | 67,452 | $241K | 0.4% | 2025-Q4 stale |
| Qube Research & Technologies Ltd added | 48,473 | $173K | 0.3% | 2025-Q4 stale |
| Jump Financial, LLC new | 38,800 | $139K | 0.2% | 2025-Q4 stale |
| Delta Investment Management, LLC trimmed | 30,930 | $110K | 0.2% | 2025-Q4 stale |
| Alyeska Investment Group, L.P. trimmed | 70,293 | $100K | 0.2% | 2025-Q1 stale |
| Tidal Investments LLC new | 23,887 | $85K | 0.1% | 2025-Q4 stale |
| LAZARD ASSET MANAGEMENT LLC new | 23,305 | $83K | 0.1% | 2025-Q4 stale |
| FAS Wealth Partners, Inc. | 22,625 | $81K | 0.1% | 2025-Q4 stale |
| Quadrature Capital Ltd new | 16,749 | $78K | 0.1% | 2025-Q3 stale |
| Lighthouse Investment Partners, LLC new | 20,513 | $73K | 0.1% | 2025-Q4 stale |
| Castleview Partners, LLC trimmed | 32,594 | $72K | 0.1% | 2025-Q2 stale |
| Balyasny Asset Management L.P. new | 19,058 | $68K | 0.1% | 2025-Q4 stale |
| Walleye Capital LLC new | 11,467 | $53K | 0.1% | 2025-Q3 stale |
| Cubist Systematic Strategies, LLC new | 11,424 | $53K | 0.1% | 2025-Q3 stale |
| Squarepoint Ops LLC new | 14,341 | $51K | 0.1% | 2025-Q4 stale |
| OPPENHEIMER & CO INC | 20,000 | $44K | 0.1% | 2025-Q2 stale |
| Point72 Asia (Singapore) Pte. Ltd. new | 9,077 | $42K | 0.1% | 2025-Q3 stale |
| Jefferies Financial Group Inc. trimmed | 10,925 | $39K | 0.1% | 2025-Q4 stale |
| JPMORGAN CHASE & CO new | 536 | $2K | 0.0% | 2025-Q4 stale |
| Credit Agricole S A | 250 | $355 | 0.0% | 2025-Q1 stale |
| RHUMBLINE ADVISERS | 72 | $257 | 0.0% | 2025-Q4 stale |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. | 0 | — | 0.0% | 2025-Q2 stale |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.